The following letter is used with permission from the Caliper Hiring Manual, published by Caliper, Princeton, New Jersey.
Thank you for taking the time to meet with me. I enjoyed having the opportunity to learn about your experiences and interests. While I was very impressed with your background, other candidates whom we have interviewed are more closely matched with the role we are seeking to fill. We will keep your resume on file in case an opening occurs in an area that more closely matches your skills and abilities.
Thank you, again, for your interest in working with us.